Telephone-exchange system.



N.-as5,o47. PTBN'TED Nov'. 6, 19de.l

H. G. WEBSTER.

TELEPHONE EXCHANGE SYSTEM.

APLIoATIoH FILED nu 7. 1903.

' tems, of which the fol owing is a ful To all whom it may concern,.-

UNITED STATES PATENT oEEioE.

HARRY G. WEBSTER, OF CHICAGO, ILLINOIS, ASSIGNOR TO STROMRERG- CARLSOIWTELEPHONE MANUFACTURING COMPANY, OF ROCHESTER,`

NEW YORK, A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE sYsTEM.-

B it knownthat I, HARRY G. WEBSTER, a citizen of the` United States, 'residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Tele hone-Exchan e 1Sysc ear, concise, and exact description, reference be ing had to the accompanying drawing, forniingvla part of this speciiication.

y invention relates to telephone-exchange systems, and is particularly -well adapted for use in conjunction with systems employing a multiple switchboard at the central exchange and a common source of current located at the central exchange adapted to supply both si naling and talkin currents tothe telephoneines leading to su scribers substations.

The principal objects of my -invention are to provide a system employing what may be known as a two-wire multiple circuitthat is, a switchboard-circuit in which there are but two jack-contacts and but two wires or conductors led to each line-jack; to provide asystem in which bothI of the j ack-contacts are ermanently connected with the telephoneine limbs, but in which the actuation of the cut-off relay is prevented by a norinal short circuit of a cut-ol'-relay winding which is normally and preferably permanently connected' in circuit with a telephoneline limb; and to providek a system in which the testing-contacts of the line-jacks are normally directly connected with the ground, whereby any inductive or static disturbances may not interfere with the proper operation the busy-test circuit employed.

Other objects of my invention will bevat once apparent to those skilled in the art.

In general, In 4,invention provides 'a'system in which tiie telephone-line limbs are each connected with opposite Aterminals of the common source of current locatedat the central'exchange., One ol the line-limbs includes in itscircu'it the winding of a line-sig-y nal or line-relay. The other line-limb normally includes one winding oi a cut-off relay, this winding, however, being normally shortcircuited through a ow-resistance shunt, this shunt being closed y the normal back contact of an armature of the cut-oil` relay.y The insertion of the plug of an operators Specification of Letters Patent.

Application filed May 7. 1903. Serial No. 156,068.

`to cause the attraction of its subscribers substation.

Patented Nev. 6, 19oe.

cord connecting circuit within a line-jack serves to close a circuit throu h a second cumulatively-wound winding o? the cut-off relay, whereby the cut-off relay is actuated armatures, the attraction of one of the armatures serving to destroy the control of the yline-signal by the switching apparatus installed at the suhscribers substation, and the attraction of the other armature serving to break the continuity of the low-resistance circuit in shunt of the first yWinding of said cut-of-relay, and upon reaching its front contact to close a low-resistance shunt-circuit about the second windi ofthe cut-off relay, whereby the contacts o the line-jacks are both connected directly with the telephone-line limbs through circuits which are entirely non-inductive. Thus an entirely non-inductive path is afforded between .the telephone-line Jacks andthe The necessary im-` pedance lto prevent the short-circuiting of voice-currents through'the source of current or common battery at the central station is provided for one line-limby by the permanent inclusion of the line-signal, which may desirably take the form of a line-relay adapted to control a local circu`it through a line-signaling lain ,and for the other line-limb through the sai first winding of the cut-ofi rela 'it being remembered that Vupon the estab ishnient of a connection between the cord connecting apparatusand the telephone-line the' low-resistance and non-inductive circuit in shunt of `this wmding is opened, whereupon the batterycurrent must e supplied to the substation ap aratus through a winding of the cut-,ofi relay. Any suitable cord con? necting ap aratus may be employed, andany desirable usy-test circuit may be applied thereto.r In connection with the test-circuit employed it may be noted that one terminal 9 of the common battery at the central exchange is connected with thegi'ound. y One `of the contacts of the line-jacks, which may also serve as thetest-thimble for testingthe condition of a line, is normally connectedA through a windin g of the cut-off relay with the grounded terminal of the common batte The grounded connection of the test-thimb e prevents variations in the potential thereof, due to inductive or static disturbances, which inmany systems of the prior art fre- ICO quently cause the false operation of the busytest circuits employed.

My invention will be readily understood by. reference to the accompanying drawing,

diagrammatically illustrating a system-constructed in accordance therewith.

At each of the substations A and B, I have illustrated the usual subscribers substation apparatus, comprising a switch -,hook 1,

1o which when in its normal depressed condition, due to the Weight of the receiver 2, serves to connect between the line-limbs 3 and' 4 the call-bell 5 and the serially-connected condenser 6. When the receiver 2 is removed from the switch-hook 1, a condnctively continuous circuit between the line-limbs is closed'through the transmitter 7 and the primary 8 of an induction-coil Whose secondary 9 is connected with the receiver 2. The linelimb s,3 and 4 lead to 'the central station,

where they are connected each with a terminal of the common battery'lO. Thelinelimb 4 permanently serially includes in its f circuit the winding of a line-signal or line- 2 5 relay 11, whose 'armature 12 when inlits forward attracted position normally closes a local circuit through the line signaling-lamp 13, the continuity of this local circuit, however, being further controlled by the armature 14 of a cut-off relay 15, a winding 16 of which is normally included in the circuit between the line-limb 3 and the positive grounded terminal of the common battery 10. A second armature 17 of the cut-off relay 15 serves when ,in its normal'retracted position to closea low-resistance shunt-circuit about the winding 16, whereby the line-limb 3 is normally directly connected with the positive grounded pole of the common battery 10 4o through a circuit including the armature 17, its back contact 18, and the conductor 19. When in its forward attracted position, the' armature 17 and its front contact 20 serve to directly connect the line-limb 3 with the sleeve-contacts 21 21 of the answering-jack 22 and the line-calling jacks 23 23, the tip-contacts 24 24 of these jacks being preferably permanently connected with the line-limb 4, as shown. y A The operators cord connecting apparatus for connecting one substation with another for conversation com rises an answering- ,plug 25 anda calling-p ug 26, whose ti -contacts 27 and 28 may be connected by t e tip- 5 5 strand 29, whose conductive continuity is interrupted by the `serially-connected condenser 30. The sleeve-contacts 31 and 32 are connected by means of a sleeve-strand 33. The supervisory relays 34 and 35 are 6o each connected between the ne ative pole of the common battery 10 and t e tip-strand- 29,l one 'on either side of the condenser 30. The armatures 36 and 37 of these supervisory relays serve when in their normal unattracted positions to respectively. close a local illumithese lamps, however, bein nating-circuit through the supervisory si maling-lamps 38 and 39, the circuit throug further controlled by the armature 40 o a controllingrelay 41, which is connected between the negative pole of the battery 10 and the sleevestrand 33. When in its forward attracted position, the armature 40, in conjunction with its front contact 42, serves to connect the negative pole of the common battery 10 with the armatures 36 and 37.

Theusual listening-key 43 is provided, by means of a manipulation of which the opera-I tor may connect her `telephone setl 44, through a serially-connected condenser 45, into a bridged relation With the cord-circuit. A test-winding 46, inductively related to the induction-coil of the operatorie telephone set, is connected between the contact 47 and the positive grounded pole of the common battery 10. The ringing-key 48 when manipulated in the n". aimer well understood by those skilled in the art serves to connect the ter-1 minals of the alternatin -current generator" 49 with the cord-strands eading to the calling-plug 26.

The operation of my improved system may be described as follows: A subscriber at substation A, desiring a telephonie connection with some other subscriber, such as the subscriber located at substation B, removes his receiver 2 from its switch-hook 1, Whereupon the switch-hook assumes the` position shown in the drawing, thereby closing ya conductively continuous circuit, whichA may be traced as follows: from the negative pole of the. common battery 10 through the linerelay 11, the line-limb 4, switch-hook 1, primary winding 8, transmitter 7, line-limb 3, armature 17, contact 18, and conductor 1 9.to the positive grounded pole of the common battery 10. Current flowing through this circuit causes an. actuation of the line-signal 11, whereby the attraction ofthe armature 12 serves to close a local circuit through the line-signaling lamp 13, thereby causing the illumination thereof to notify ther operator that a connection with some other telephoneline is desired. In addition to the circuit traced from the line-limb 3 through the ar.- mature 17 and its back contact 18 to the positive pole of the battery there Iis also a circuit through the winding 16 of the cut-off IOO relay 15; but this circuit is of comparatively high resistance, and suflicient current cannot be forced through this winding to causethe attraction of the cut-oif-relay armatures 14 and 17. The. oierator at the'c'entral ex-v change answers t e signal caused-by the illumination of the lamp 13 by inserting the answering-plug 25 of her cord-circuit within the answering-jack 22. This causes thc closure of a circuit which. may be traced as follows: from the negative pole of the common battery 10 through the` Winding of the' .tion of the armature 17, however, from its back contact'18 serves to break 'contact 21 `of the -the winding 51A 41, ythe sleeve- 31, the sleevejack 22, the conductor 50,

supervisory controlling-relay strand 33, the sleeve-contact thence through larmature 17v to the conductor v52 and 'the vback rcontact 18, and the conductor 19 to the positive pole of lthe battery 10. The consequent energization of the cut-ofi ,relay causes the attraction of the armatures Ligand 17. The attracthe circuit just traced through the 'windin 51. However, the flow of current throug this winding 1s maintained for a short interval throu h a circuit which may be traced through t e winding 51, the winding 16, Iand thence to the positive pole'of the battery 10. f The armature 17I upon reachingl its front contact 2O serves to close a low-resistance circuit'in4 the winding 15, this low-resistance shunt of circuit'being traced from the jack-contact 21 through the conductor 50,.the contact 20, the armature 17 the conductor 52, and thence, as before, through the cut-off-relay windin 16 to the 10. AT 's actuatlon of the cut-off relay serves, first, by the attraction of its armature 14 to destroy the control of the line-signal by thehook-switchat the subscriber's substation; second, to break thecontinuity of the low-resistance circuit in shunt of the cutoff-relay winding 16, and, third, to'connect a low-resistance circuit in shunt of the cutoff-relay winding 51, whereby the jack-'contact 21l is connected through a non-inductive l,circuit directly with the line-limb 3. It will zatlon of the through t e relay closed. T e

be seen that under normal conditions with lthe armature 17 1n connection with its back contact 18 there is a grounded connection through the windings of the cut-off relayv with the sleeve-contacts of the line-jacks. These contacts are thus normally maintained at the zero potential of theearth and are therefore free from vinductive and static disturbances likely toI affect' the operation of 4the busy-testapparatus employed. vThe closure of the hereinbcfore-traced circuits through the supervisory controlling-relay 41 ,armature 42, superviso signaling-lamps 38 and 39 is armature 37 is for the present not attracted by its relay-m et, whereupon a circuit is cios'ed throug the supervlsorysignaling-lamp 39 to cause its illumination. The armature 36 of the su ervisory relay 34', however, is attracted by tige energirelay 34, the circuit throu h this relay being traced as follows: from t e negative ole ofthe common battery 10 34, the tip-strand 29, the tip-contact 27 of the answering-plug 25, the tip-contact 24, the line-limb 4,- the switchhook 1, theprimary coil 8, the transmitter 7,

of the cut-off relay, and,

positive pole of the battery ,strand 29, leading to circuit through thereby indicatl the grounded terminal lof the t e illumination of the supervisory signalingl' lamp 38. After thus establishing connection-between her cord-circuit and the tel` phone-line to substation A Ithe operato. manipulates her listening-key 43 to connect her telephone set in scriber at substation A ascertains the -nu'mber of the subscribers substation with which communication is desired. Learning this to be substation B, the operator applies the tri v-contact 28 of her calling-plug 26 to t e sleeve-contact 21 of a line-jack 23, associated with the line to substation B. If this line is already in use and some other o erator at some ot er position on the multiplie switchboard has inserted the plug of a lsimilar cord-circuit within anyr one of the linejacks, the application of the test-contact 28 to the sleeve-contact 21 of such will cause the closure of a circuit, which may be traced as follows: from the positive grounded pole of the battery 10 through the testi-windingl 46, the contact 47, the upper spring of t e listening-key 43, the sleevethe contact 28, the sleeve-contact 21, the some other cord-circuit, the sleeve-strand 33I of the corresponding cord-circuit, and the corresponding superviso controlling-relayI 4'1 tothe negative pole diy the common battery 10. he momentary closure of such a the test-winding 46 causes a click in the operators telephone-receiver, to her that the tested line v1s in use. If at e-time of making the busy test the subscriber at substation B has removed his tele hone-receiver from the switchhook, but his ine-signal has` not as yet been answered by theinsertion of al the answering-jack, the test-circuit may be traced from the -testingtip contact 28 bridge of the cord-cir-y cuit and by communication with the suba busy, line' sleeve-contact 32 of plug within through the conductor 50, the winding 51 of I the cut-off relay, line-limb 3,v transmitter 7, fprimary coil 8, switch-hook 1, line-limb, 4, and line-relay 11'l to the negative pole of the common battery 10. This circuit, aswell as that previously traced, will produce a click. in the operators telephone-receiver to ive her the characteristic busy-.test signal. I the line to substation B is not 1n use, no current will be caused to flow through the test-winding 46,`for the reason that the test-contacts 21 oi' thev line-jacks are normally connected with te'ry 10, with which the test-winding 46 is also connected. The fact that the test-contacts-21 of the line-jacks are thus provided with this normal ground connection prevents common batof the generator 49 with the line-limbs lead-- in to the call-bell at substation B. The su scriber at substation B in answering the signal removes his receiver from the switch- Vzo hook 1, whereupon a conductively continuous circuit is closed between the line-limbs 3 and 4, thereby causing the closure of a circuit through the supervisory relay 35, whereupon the armature 37 is attracted to cause the extinguishrnent of the lamp 39. The re2 moval of the receiver at substation B lfrom its switch-hook will not cause the illumination of the corresponding line si nal'ing-lamp 13, due to the armature 12 of t e line-relay 11, for the reason that the insertion of the calling-plug 26 within the line-jack' 23 will have caused the actuation of the cut-0H relay 15 by a circuit which may be traced through the relay-winding as follows: from the negative pole of the battery 10 through the supervisory controlling-relay41, the sleeve-strand 33, leading to the sleeve-contact 32, the sleeve-contact 21 of the jack 23, the conductor 50, the winding 51 of the cut-off relay, and the winding 16 thereof' to the positive pole of the battery 10. The ow of current throu h this circuit will cause the energization of t e cut-off relay 15, whereupon its armatures 14 and 17 will be attracted, the attraction of the armature 14, as previously described, serving to destroy the substation control of the linesignal, and the attraction of the armature 17 serving tov break the, continuity of the' lowresistance shunt about the winding 16 and to closel a low-resistance circuit in shunt of the winding 51 of the cut-off relay. The teleph onic connection between the lines leading to substations A and B being thus established, the subscribers may converse with one another over a circuit containing but the single relaycontact between the armature 17 and the contact 20. Upon having finished the conversation, either subscriber upon replacing his receiver upon the switch-hook breaks the ,con-

tinuity of the conductive. circuit previously traced through the associated supervisory relay, whereupon the supervisory-relay armature is retracted into its Inormal position, thus closing ai circuit 'through the associated supervisorysignaling-lampto notify the centralstation operatory ofthe desired disconnection. The operator thereupon'removesthe cordcircuit plugs from the. jacks, whereupon the cut-oif-mfay armatures are retracted into their normal position, thus restoring the apparatus to its Inormal condition e While I have herein shown and described one preferred embodiment of my invention,

it will be apparent to those skilled in the art that many modifications may be em loyed without departing from the spirit ticreof. I do not, therefore, wish to limit myself to the precise disclosure herein set forth; but,

Having described my invention, I claim as new and desire tosecure by Letters Patent- 1. In a tele hone-exchange system, the combination with a telephone-line extending by its limbs from a substation to an exchange, of switching apparatus at the substation adapted to control the conductive continuity of an electrical path between said line-limbs, a source of current at the exchange for supplying talking and signaling currents to said line, said line-limbs-being permanently connected each to an opposite terminal of said source of current, a ine-relay permanently serially included in one of said line-limbs, a line-signal controlled by said relay, a cut-off relay having a winding permanentlyseriallv included in the second ine-limb, a normally closed low-resistance path in shunt of said winding of said cut-off relay, a line-jack lhaving a contact perinanently connected with one of said line-limbs, cord connecting apparatus for connecting said line with another. for conversation, a second cumulative winding for said cut-off relay, and means whereby the connection of said cord connecting ap aratus with said line causes the closure o an electric circuit through said secondwinding of the cut-off relay to cause an actuation thereof to destroy the substation control of said line-signal and to break the continuity of the low-resistance path in shunt of said first winding of said cut-off relay.

2. In a telephone-exchange system, the combination with a teleplione-liiie extending by its limbs from a substation to an exchange, of switching apparatus atthe substation adapted to control the conductive continuity of an electrical path between said line-limbs, a source of current at the exchange for supplying talking and signaling currents to said line, said line-limbs being connected each to an opposite terminal oi said source of current, a line-relay permanently serially included in one of said linelinibs, a line-signal controlled by said relay, a cut-off relay having awinding permanently serially included in the second line-limb, a normally closed low-resistance path in. shunt of said winding of said cut-off relay, a linejack having .a contact permanently connected .with each of said line-limbs, cord connecting apparatus for connecting said line with another for conversation, a second .cumulative winding for said cut-off relay,

IOO

IIO

the substation control ofsaid line-signal and to break the continuity of the low-resistance path in shuntl of said first winding of said cutofll relay. y

3. In a telephone-exchangesystem, the combination with a telephone-line extending by its limbs from a substation to an exchange, of switching apparatus at the substation adapted to control the conductive lcontinuity of an electrical path between said line-limbs, a source of current at the exchange for supplying talking and signaling ycurrents to said line, said line-limbs being ,permanently connected each -to lterminal of said source of` current, a

an opposite ine-relay serially included in one of said line-limbs', a ine-signal controlled by said relay, a cutoff relay having a winding permanently serially included in the secondi line-limb, a normally closed low-resistance path in shunt of said winding ofsaid cut-off relay, a line-jack having a contact permanently connected l with each of said line-limbs, cord connecting control of said line-signal and to break thel Y continuity ofthe low-resistance path in shuntof said first winding of said cut-off relay.

4. In `a telephone-exchange system, the

combination with a telephone-line extending vby its limbs from a substation to an exchange, of switching apparatus at the substation adapted to control the conductive continuity of an electrical path between said line-limbs, a source of current atthe exichangc for supplying talking and signaling currentstoly said line, said line-limbs being permanently connected each to an o posite terminal of said source of current, a ine-relay permanently serially included in one of said line-limbs, a line-signal controlled by said relay, a cut-ofi` rela having a winding ermanently seriall inchided in the second ine-limb, a norma ly closed low-'resistance'v y path in shunt of said winding of said cut-ofil relay, aline-jack having a contact connected with each of said line-limbs, cord connecting apparatus for connecting said line with another for conversation, a second cumulative winding for said cut-off relay', and means whereby the connection of said cord connecting apparatus with said line vcauses the closure of an electric circuit through said second winding of the out-off relay to cause an actua tion thereof to destroy the substation control of said line-signal and to break the continuity of the low-resistance path in shunt of said first Winding of' said cut-off relay.

' 5. In a telephone-exchange system, the

combination with a telephone-line extending by its limbs from a substation to any exc ange, of switching apparatus at the substation adaptedto control the conductive continuity of an electrical path between said line-limbs, a source of current at the exchange `for supplying talking and signaling currents to ysaid line, said linie-limbs being connected each to an opposite terminal of said source of current, a line-relay serially included in one of said line-limbs, a line-signal controlled by said relay, a cut-off relay having a winding permanently serially included in the second line-limb, a normally closed low-resistance path in shunt of said 'winding of said cut-off relay, a line-jack having a contact permanently connected with each of said line-limbs, cord connecting aparatus for connecting said line with another or conversation, a second cumulative winding for said cut-off relay free from currentfiow when the cord connecting apparatus is disconnected from the line, and means .whereby'the connection of said cord connecting ap aratus with said line causes. the closure o an electric circuit through said second winding of the cut-ofi relay to cause an actuation thereof to destroy the' substation control of'said line-signal and to break the continuity of the low-resistance path in shunt of said first winding of said cut-ofi' l relay.

6. In a telephone-exchange system, the combination with a telephone-line extending by its limbs from a substation to an exchange, of switching ap aratus at the substation adapted to contro the conductive continuity of an electrical path between said line-limbs, a source of current at the exchange for supplying talking and signaling currents to said line, said line-limbs being connected each to an opposite terminal of said source of current, a line-relay perma- -nently serially included in one of said lineliinbs, a line-signal controlled by said relay, a cut-oli relay having a winding serially included in the second line-limb, a normally` closed low-resistance path in shunt of said winding of said cut-ofi` relay, a line-jack having a contact permanently connected with IOO each of said line-limbs, cord connecting apparatis for connecting said line with another or conversation, a second cumulative Winding for said cut-ofi' relay, and means whereby ythe connection of said cord connecting apparatus with said line causes the closure of an electric circuit through said second winding of the cut-ofl'` relay to cause an actuation thereof to destroy the substation control of said line-signal and to break the continuity of the low-resistance path in shunt of said first .winding of said cut-ofi' relay.

7. In a telephone-exchange system, the

combination with a telephone-line extending by lts limbs from a substation to an exchange, of switching apparatus at the substation adapted to control the conductive continuity of an electrical path between said line-limbs, 'a source of current at the ex- .line-limbs, cord connecting apparatus for connecting said line with another for conversation, a second cumulative winding for said cut-oifrelay, and means whereby the connection of said cord connecting apparatus With said line causes the closure of an electric circuit through said second Winding of the cut-oil' relay to cause an actuation thereof to-'destroy the substation control of said line-signal and to break the continuity of the low-resistance path in shunt of said rst Winding of said cut-off relay.

8. In a tele hone-exchange system, the combination w1th a telephone-line extending bg' its limbs from a substation to an exc ange, of switching'a'pparatus at the substation adapted to control the conductive continuity of an electrical path between said line-limbs, a source of current at the exchange for supplying talking and signaling currents to said line, said line-limbs being connected' each to an opposite terminal of said source of current, a line-relay serially included in one of said line-limbs, a line-signal controlled by said -line-relay, a cut-off relay having a winding seriall included in the second line-limb, a lnormal y closed low-resistance path in shunt of said winding of said cut-0H relay, a line-jack having a contact ermanently connected with each of said ine-limbs,- cord connecting apparatus for connectingsaid line withhanother for conversation, a second cumulative winding for said cut-off relay freefrom current-flow when the cord connecting apparatus is disconnected from the line, and means whereby the connection of said vcord connecting apparatus with saidline'causes the closure of an electric circuit through said second winding of the cut-off relay to cause an actuation thereof to destroy the substation control of said vline-signal and to'break the continuity of the low-resistance path inshunt of said first Winding of said cut-ofi'` relay.

9. In atele hone-exchange system, the combination with a telephone-line extending blyits limbs from a substation to an excange, of switching apparatus at the substation adapted to control the conductive continuity of an electrical path between said line-limbs, a source of current at the exchange for su plying talking and si naling currents to sai line, said line-limbs being permanently connected each to an opposite terminal of said source of current, a line-relay serially included in one of said line-limbs, a line-signal controlled by said line-relay, a cut-ofi relay having a winding serially included in the second line-limb, a normally closed low-resistance path in shunt. of said winding of said cut-oi'l relay, a line-jack having acontact connected with each of said line-limbs, cord connecting apparatus for connecting said line with another for conversation, a second cumulative winding for said cut oli relay, and means whereby the connection of saidcord connecting apparatus with said line causes the closure of an electric circuit through said second winding of the cut-oil relay to cause an actuation thereof to destroy the substation control of said line-signal and to break the continuity of the low-resistance path in shunt of said first winding of said cut-oit relay.

10. In a telephone-exchange system, the combination with a telephone-line extending b its limbs from a substation to an exchange, ci, switching apparatus at the substation adapted to control the conductive continuity of an electrical path between said linelimbs, a source of current at the exchange for suplying talking and signaling currents to sai line, said line-limbs being connected each to `an opposite terminal of said source of current, a line-relay permanently serially included in one of said line-limbs, a line-signal controlled by said line-relay, a cut-ofi relay having a winding permanently serially included in the second line-limb, a normally closed low-resistance path in shunt of said winding of said cut-ofi relay, a line-'ack having a contact connected with eacli of said line-limbs, cord connecting apparatus for connecting said line with another for conversation, a second cumulative winding for said cut-ofi relay, and means whereby the connection of said cord connecting apparatus .with said line causes the closure of an electric circuit through said second winding of the cut-off rela to cause an actuation thereof to destroy the substation control of said linesignal and to break the continuity of the lowresistance path in shunt of said irst winding of said cut-off relay.

11. In a telephone-exchange system, the combination with a telephone-line extending ,by its limbs from a substation to an cxchange, of switching apparatus at the substation adapted to control the conductive continuity of an electrical path between said line-limbs, a source of current at the exchange for supplying talking and signaling currents to said line, said line-limbs being connected each to an opposite terminal of said source of current, a line-relay serially lOO IIC

` connection of said cord connecting apparatus I said winding of said cut-ofi relay,

line-signal. controlled by said line-relay, a

Vlay having a winding permanentlyv serially included in the second line-limb, a normally included in one' of said line-limbs, a line-sigl nal controlled by said line-relay, a cut-ofi' reclosed low-resistance path yin shunt of said winding of said cut-ofi' relay, a line-'ack having a contact connected with eac-i1 of said line-limbs, cord connecting apparatus for connecting said linewith anotherfor conversation, a secondcumulative winding for said cut-off relay free from current-flow when the cord connecting apparatusy is disconnected from the line, and means whereby the with said line causes the closure of anelec-A tric -circuit throughl said second windingl of the cut-off relay to cause an actuation ,thereofl to`destroy the substation control of said line-signal and to break the continuity of the low-resistance path in shunt of ,said first winding of said cut-off relay.v n

12. fn a telephone-exchange system, the combination with a telephone-line extending b its limbs from a substation to an exv ciirange, `of switching apparatus at the substation adapted to control the conductive continuity of an electrical path between said line-limbs, a source of current at the exchange for supplying talking and signaling currents to said line, said line-limbs being connected each to an opposite terminal of said source of current, a line-relay permanently serially included in one of said linelimbs, a line-si nai controlled by said linerelay, a cut-o relay-having a winding serially included in the second line-limb, a normally closed low-resistance path in shunt of a line-jack having a vcontact connected with each of said line-limbs, cord connecting apparatus lfor connecting said. line with another for conversation, a second cumulative winding forsaid cut-ofi' relay', and means whereby the connection of said cord connecting apparatus with said line causes the closure of an electric circuit through said second windin of the cutoff rela tocause an actuation t ereof to destroy tiie substation control of said line-signal and to break the continuity of the lowresistance path in shunt of said first winding of said cut-off relay.

13'. n-a telephone-exchange system, the combination with a telephone-line extending bv its limbs from a substation to an exchange, oi switching apparatus at the substation adapted to-control the conductive continuity of an electrical path between said line-limbs, a source of current at the exchange for s v T plying talking and signaling currents to said ine, said linelimbs being permanently connected each tov an opposite terminal of said source of current, a. line-relay permanently serially included in one of sald line-limbs, a

cut-off relay having a winding permanently serially included in the second line-limb, a v

normally closed low-resistance path in shunt of said winding of said cut-ofi` relay, a linet y jack having a cont act permanently connected with each of said line-limbs, cord connecting apparatus for connecting said line with another for conversation, a 'second cumulative Winding for said cut-off relay, and means whereby the connection of said cord connect-y ing ap aratus with said line causes the closure o an electric circuit through said second winding of the cut-off rela to cause an actuation thereof to destroy t 1e substation control of said line-signal and to break the continuity of the low-resistance path in shunt of said first winding of said cut-'off relayand to afford a non-inductive electrical path betweensaid jack-contacts and the line-limbs. 14, In a telephone-'exchange system, the combination with a telephone-line extending by its limbs from a substation to an exchange,` of switching apparatus at the substation adapted to control the conductive continuity of an electrical path between said line-limbs, a source of current at the exchange for suplying talking and signaling currents to said- Ene, said line-limbs being connected each to an opposite terminal ofsald source of current, a line-relaypermanently serially included in one of said line-limbs',l by said line-relay, winding permanently serially included in the second line-limb, a normally closed low-resistance ath in shunt of said windingof said cut-off re ay, a line-jack having a contact per- -manentl'y connected with each of said linea line-signal controlled 95 a cut-ofi relay having a limbs, cord'connec'ting ap aratus for connecting said llne with anot erfor conversat tion, a second cumulative winding for said, cut-ofi relay, -means whereby the connection of said cord connecting apparatus with said linecauses the closure of an'electric circuit through said second windin of the cut-off -relay to cause an actuation t ereof to destroy 'the substation control of said line-signal and :to break the continuity of the I l O low-resistance path in shunt of said first winding of said cutoff relay, and means upon actuation of said cut-off relay for` affording a non-inductive electrical path between said j ack-contacts and the line-limbs. y i 15. In 'a telephone-exchange system, the combination with a telephone-lineextending b its limbs from a substation to an exchange, oi7 switching apparatus at the substation adapted to control the conductive continuity of an electrical path between said line-limbs, a source ocurrent at theexchange for suplplying -talking and signaling currents to said ine, said line-limbs being permanentlyconnected each to an opposite terminalv of sald source of current, a line-relay permanently serially included in one of said line-limbs, a line-signal controlled by said 4line-relay, a cut-ofi relayv having a Winding serially included inthe secnd line-limb, a normally closed low-resist ance path in shunt of said winding of said cuty off relay, a line-jack having a contact pennanently connected with each oi said line-limbs, cord connecting apparatus for connecting said line with another for conversation, a second cumulative winding for said cut-oli relay, and means whereby the connection of said cord connecting apparatus with said linecauses the closure of an electric circuit through said sec ond windin of the cut-off relay to cause an actuation t ereof to destroy the substation vcontrol of said line-signal and to break the continuity of the lcw-resistance path in shunt of said first winding of said cut-off relay, and to aord a non-inductive electrical path between said jackcontacts and the line-limbs.

16. in a telephone-exchange system, the combination with a telephone-line extending by its limbs from a substation to an exchange, or' switching apparatus at the substation adapted to control the conductive continuity of an electrical path between said line-limbs,

Va source lof current at the exchange for suplying talking and signaling currents to said ine, said line-limbs being permanently connected each to an opposite terminal of said source ci current, a liiiei'clav permanently serially included iii one ci said inali'mlis, a linesignal controlled by said line-relay, a cutofl relay having a winding permanently serially included in the second line-limb, a normally closed low-resistance path in shunt oik said winding of said cut-ofil relay, aline-j ack having a contact connected with each of said line-limbs, cord connecting apparatus for connecting said line with another for conversation,- a second cumulative winding for said cut-oil' relay, means whereby the connection of said cord connecting apparatus withlsaid line causes the closure of an electric circuit through said second winding of the cut-oil relay to cause an actuation thereof to destroy the substation control of said line-signal and to break the continuity of the low-resistance path in'shunt of said lirst winding of said cutoil` relay, and means upon actuation of said cut-cd.v relay for ailording a iioii-iiuluctive electrical path between said jack-contacts and the line-limbs.

17. ln a telephoneecxchange system, the combination with a telephone-line extending by its limbs' from a substation to an exchange, of switching apparatus at the substation adapted to control the conductive continuity of an electrical path between said linelimbs, a source of current at the exchange for su lying talking and signaling currents to said) ine, said ine-limbs being connected each to an opposite terminal of said source of" current, a line-relay serially included in one of said line-limbs, a line-signal controlled by said line-relay, a cut-oli relay having a winding permanently serially included in the second line-limb, a nor* --liy closed low-resist sanear ance path in shunt of said winding of said cutofi relay, a linc-j ack having a Contact permanently connected with each of said line-linibs, cord connecting apparatus for connecting said line with another for conversation, a second cumulative winding for said cut-oif relay, means whcreby the connection of said cord connecting apparatus causes the closure of an electric circuit through said second winding of the cut-ofi relay to cause an actuation thereof to destroy the substation control of said line-signal and to break the continuity of the low-resistance path in shunt of said first winding ol' said cut-oli' relay, and means upon actuation of said cut-off relay for aliording a nen-inductive electrical ath between said jack-contacts and the lineimbs.

18. In a telephone-exchange system, the combination with a telephone-line extending by itslimbs from a substation to an exchange, of switching apparatus at the substation adapted to control the conductive continuity of an electrical `path between said line-limbs, a source of current at the exchange for supplying talking and signaling currents to said line, said liiiellimbs being permanently connected each to an opposite terminal of said scui'cc of current, a liuc-relay serially included m ciic cl said liiic-liiiibs, ii liuc-signal c011- trolled by said line-rela a cut-oil relay having a winding serial y included in the second line-limb, a normally closed lowresistance path in shunt of said winding of said cut-'oli' relay, a line-jack having a contact connected with each of' said line-limbs, cord connecting apparatus for connecting said line with another for conversation, a sccoiid cumulative winding for said cut-oli" rclay, means whereby the connection of said cord connecting apparatus with said line causes the closure of an electric circuit through said second winding of tho cut-oil' rolay to cause an actuation thereof, to destroy the substation control of said line-sigiial and to break the continuity of thc low-resistance patl'i in shunt of said iirst winding oi said cutoli` relay, and means upon actuation of said cut-oiil relay for alfording a non-inductive electrical path between. said jaclvcoutacts and the line-limbs.

i9. in a telephone-exchange system, the combination with a telephone-line extending by its limbs from a substation to an exchange, of switching apparatus atY the substation adapted to control the conductive continuity of an electrical path between said line-limbs, a source of current at the exchange for suplying talking and signaling currents to said line, said. line-limbs being connected cachto an opposite terminal of said source of current, aline-relay permanently serially included in one of said line-limbs, a line-sigiial controlled by said line-relay, a ciit-o relay having a winding permanently serially included in the said line-limbs, a line-signal cut-eti relay, a line-jack having a contact connected with each of said line-limbs, cord p connecting apparatus for connecting said li'ne with another for conversation, a second cumulative winding forv said cut-off relay, means whereby the connection of said cord connectingapparatus with said line causes the closure o an electric circuit through said second winding of the cut-off relay to cause an actuation thereof, to destroy the substation control of said line-signal and to break the continuity of the low-resistance path in shunt of said'tirst winding of said cut-ofi relay, and means upon actuation of said cut-ori` relay for adording a non-inductive electrical path between said limbs.

20. In a telephone-exchange system, the combination with a telephone-line extending byits limbs from a substation to an exchange, of switching apparatus at the substation adapted to control the conductive continuity of an electrical path between said line-limbs, a source of current at the exchangev foilsupplying talking and signaling currents to said line, said line-limbs-being connected each to an opposite terminal of said source of current, a line-relay serially included in. one of controlled by said line-relay, a cut-oill relay having a winding 'permanently seriallyincluded in the second line-limb, a normallyclosed low-resistance path in shunt of said winding of said cut-ellrelay, a line-j ack having a contact connected with each of said line-limbs, cord con.- neeting apparatus for connecting said line with another forconversation, a second cumulative winding l'or said cut-oil relay, means \\'l1ereby the connection of said cord connecting apparatus with said line causes the elosu re ot an electric circuit through said second windingr ot' the cut-oil` relay to cause an actuation thereof, `to destroy the substation con-A trol ot said line-signal and to break the contlnlnty olI the low-resistance path 1n shunt of Y said lirst winding ol said. cut-oil relay, and

means upon actuation of said cut-oil relay for al'ording a non-inductive electrical path between said jack-contacts and the line-limbs.

2]. In ya telephone-exchange system, the combination with `a telephone-line extending by its limbs l'roni a substation to an exchange, ot switching apparatus at the substation adapted to control the conductive continuity ol"an electrical path between said` line-limbs, a source el' current at the exchange 'l'or supplying talking and signaling currents to said line, said line-limbs beingconnected each to an opposite terminal ol` said soureeol' current, a line-relay |un|nanently serially included in one ol' said line-limbs, a line-signal controlled by said line-relay, Ya `eut-oilrelay having a winding serially included in the second linclinib, a mirnntlly closed low-resistal'ice path jack-.contacts and the linein shunt of said winding of said cut-ofi relay,

a line-ack having a contact connected with eachy o said lineli1nbs,eord connecting ap a- ,ratus for connecting said line with anotlier for conversation, a second cumulative winding for said cut-off relay, means whereby the connection of said cord connecting apparatus with said line causes the closure of an 'electric circuit through said second winding of the cut-off relay to cause an actuation thereof, to destroy the substation control of said line-signal and to break the continuity of the low-resistance path in shunt of said first winding of said cut-off relay, and means upon actuation of said cut-ofi' relay for affording a non-inductive electrical path between said jack-contacts vand the line-limbs.

-22. In a telephone-exchange system, the combination with a' ,telephone-line extending byits limbs from a substation to an exchange, o switching apparatus at the substation adapted to control the conductive continuity of an electrical path between said line-limbs, a source of current at the exchange for supplyingtalking and signaling currents to said line, said line-limbs being connected each to an opposite terminal of said source of current, a line-relay serially included in one of said line-limbs, a' line-signal controlled b said line-relaya cut-off relay having a win ing included in the second line-limb, a lowresistance path in shunt. of said winding of said cut-off relay, cord connecting ap aratus for connecting said line with another 'or conversation, a second cumulative winding for said cut-ofi' relay free from current --iiow when the cord connecting apparatus is disconnected from the line, and means whereby the connection of said cord connecting apparatus with said. line causes the closure of an electrical circuit through the second winding ol said. cut-elll relayv to cause an actuation thereof to break the continuity of the lowreslstancc path in shunt of of said cut-oil relay.

23. In a telephone-exchange system, the combination with a telephone-line extending b its limbs from a substation toan exchange, ci?, switching f apparatus at the substation adapted to control the conductive continuity said first winding of an electrical path between said line-limbsfa source of current at the/exchange for su plying talking and signaling currents to said) line, said line-limbs being connected each to anopposite terminal ol said source of current, a lin e-relay serially included in one of said linelimbs, a line-signal,controlled by said linerelay, a cut-oil relay having a winding included in the second line-limb, a path in shunt oi' said winding ot'said cut-oil relay, cord connecting apparatus for connecting said line with another for conversation, a second cumulative winding for said eut-ofi' relay normall free from current-flow upon closure of the line at the substation, vand means IOS IIO

ISO

whereby the connection of said cord connect- `ing apparatus with said line causes the closure ot' an electrical circuit through the second winding oi said cut-'off relay to cause an actuation thereof to break the continuity of the path in shunt of said first Winding of said cut-ofi' relay.

24. In a telephone-exchange system, the combination with a telephone-line extending by its limbs from a substation to an exchange, of switching apparatus at the substation adapted to control the conductive continuity of an electrical pathbetweensaid linelmbs, a source of current at the exchange for supplying talking and signaling currents to said line7 said line-limbs being connected each to an oppositenterminal of said source of current, a line-relay serially included in one of said line-limbs, a line-signal controlled by said linerelay, a cut-0H relay having a winding included in the second line-limb, a path in shunt of said winding of said cut-ofi relay, a line-j ack vhaving a contact permanently connected with each of said line-limbs, cord connecting apparatus for connecting said line with another for conversation, a second cumulative winding for said cut-0H relay normally free from current-flow upon closure of the line at the substation, and means whereby the connection of said cord connecting apparatus with said line causes the closure of an elec trical circuit through the second winding of said cut-otl` relay to cause an actuation thereof to break the continuity of the path in shunt oi said first winding of said cut-ofil relay.

25. In a telephone-exchange system, the combination with a telephonedine extending by its limbs from a substation to an exchange, of switching apparatus at the substation adapted to control the conductive continuity of an electrical path between said line-limbs,

a source of current at the exchange for supplying talking and signaling currents to said line, said line-limbs beingconnected each to an opposite terminal'oi said source of current, a line-relay serially included in one of. said line-limbs, a line-signal controlled by said line-relay, a cut-oii relay having a winding included in the second line-limb, a path in shunt of said. Winding of said cut-cti relay, a line-jack having a contact connected with each of said line-limbs, cord connecting ap paratus for connecting said line with another for conversation, a second cumulative winding for said cuto'ti relay free 'from current* flow when the cord connecting apparatus is disconnected from the line, and means whereby' the connection of said cord connecting apparatus with said line causes the closure of an electrical circuit through the second winding of said cut-oiil relay to cause an actuation thereof to break the continuity of the path in shunt of said first winding of said cut-0H relay.

26. In a telephone-exchange system, the

combination with a telephone-line extending by its limbs from a substation to an exchange, of switching apparatus at the substation adapted td control the conductive continuity of an electrical path between said line-limbs, a source oi current at the exchange for supplying talking and signaling currents to said line, said line-limbs being connected each to an opposite terminal of said source of current, a line-relay serially included in one of said line-limbs, a line-signal controlled by said line-relay, a cut-ofi relay having a winding included in the second line-limb, a path in shunt of said winding of said cut-ofi relay, a line-jack having a contact permanenty connected with each of said line-limbs, cord connecting apparatus Jfor connecting said line with another for conversation, a second cumulative winding for said cut-off relay, means whereby the connection of said cord connecting apparatus with said line-causes the closure of an electrical circuit through the second winding of said cut-off relay to cause an actuation thereof to break the continuity of the path in shunt of said iirst winding of said cut-oli relay, and means upon actuation of said cut-oit relay for closing a lowresistance non-inductive electrical path between said jack-contact and the second linelimb.

27. In a telephone-exchange system, the combination with a telephoneeline extending by its limbs from a substation to an exchange, of switching apparatus at the substation adapted to control the conductive continuity of an electrical path between said line-limbs, a source of current at the exchange for supplying talking and signaling currents to said line, said line-limbs being connected each to an opposite terminal of said source of current, a line-relay serially included in one of said line-limbs, a line-signal controlled by said line-relay, a cut-off relay having a winding included in the second linelimb, a path in shunt of said winding of said cut-ofi relay, a line-jack having a contact connected with each of said line-limbs', cord ICO IOS

connecting apparatus for connecting said line A with another'i'or conversation, a second cumulative winding for said cut-ofi relay,

means wherebythe connection of said cord connecting apparatus with said line causes lthe closure of an electrical circuit through the second winding of said cut-off relay tol cause an actuation thereof to break the continuity of the path in shunt of said first winding of said cut-oil` relay, and meansupon actuation of said cut-off relay for closing a lowresistance non-inductive electrical path between said jack-contact and the second linelimb.

28. In a telephone-exchange system, the combination with a telephone-line extending b its limbs from a substation to an excliange, of switching apparatus at the substation adapted to control the conductivey 'cut-off relay, a line-jack having one contact permanently directly connected to one o1 said line-limbs and a second contac-t permanently connectedthrough a second cumulative winding of said cut-olf relay with. the

other of said line-limbs, cord connecting apparatus for connecting said line with another for conversation, and means wlieieby the insertion of a plug of said cord connecting apparatus wit 1in said jack closes a circuit through said second jack-contact and the said second winding of said cut-oil relay to cause an actuation of said cut-off relay to destroy the substation control of said 'linel signal and to'open the cireuitthrough the path in shunt of said first winding of said cut-off relay.

29. In a telephone-exchange system, the combination with a teleplione-line extending by its limbs from a substation to an eXf change, of switching apparatus at the substation-adapted to control the conductive continuity of an electrical path between said line-limbs, a source of current at the exchange for supplying/talking and signaling currents to said line, said line-limbs being connected each to an opposite terminal of said source of current, a line-relay serially included in one of said line-limbs, a line-signal controlled by said line-relay, a' cut-oli` relay .having a winding serially included in the seoond line'- limb, a normally closed low-resistance path in shunt of said winding of said eut-off relay, aline-j ack having one contact directly connected to one of said line-limbs and a second contact connected through a second cumulative winding of said cut-oil relay with the other of said line-limbs, cord connecting apparatus 'for connecting said line with another for conversation, and means whereby the insertion of a lug of said cord connecA ing apparatus Witliin said jack closes a circuit through said second jack-contact and the said second winding of said cut-off relay to eau-se an actuation of said eut-off relay to destroy the substation control of said liliesignal and to openthe circuit through the path in shunt of said first winding of said cut-off relay.

30. In a telephone-exchange system, the combination with a telephone-line extending by its limbs from a substation to an -exchange, of switching apparatus at the sub station adapted to control the conductive continuity of an electrica-l path between said line-limbs, a source of current at the exchange for supplying talking and signaling currents tosaid line, said line-limbs being permanently connected each to an o )posite terminal of said source of current, a line-re'- lay permanently serially included in one of said line-limbs, a line-signal controlled by said'line-relay, a cut-oil relay having a winding permanently serially included in the second line-limb, a normally closed low-resistance path n1 shunt of said winding of said cut-eti" relay, a. line-jack having one contact permanently directly connected to the lineimb including said linerelay and a second contact permanently connectedthrough a second cumulative winding of said cut-ofi' relay with the other of said line-limbs, cord -connecting apparatus for connectingsaid line with another for conversation, and.

means whereby the insertion of a plug of said cord connecting a'iparatus within said jack closes a circuit through said second jackcontact and the said second winding of said cut-oliiI relay to cause an actuation. of said cut-off relay todestroy the substation control of said signal and to open the circuit through the path in shunt of said first winding of said cut-oil" relay.

31. In a telephone-exchange system, the

combination with a telephone-line extending by its limbs from a substation to an exchange, of switching apparatus at the substation adapted to control the conductive continuity of an electrical ypa th between said line-limbs,v a source oi. current at the exchange for supplying talking and signa-ling currents to said line, said line-limbs being connected each to an opposite terminal of said source of current, a line-relay serially included in one of said line-limbs, a line-signal controlled by said line-relay, a cut-olf relay having a winding serially included in the second line-limb, a normally closed lowresistance path in shunt of said winding of said cut-ofi relay, a line-j ack having one contact directly connected to the line-limb including said line-relay and a second contact connected through a second cumulative winding of said cut-'oil'l relay with they other of said line-limbs, cord connecting ap )aratus for connecting said line with another ior conversation, and means Wliereby the insertion of a plug of said cord connecting apparatus within said jack closes a circuit through said second j ack-contact and the said second winding of said cut-ofi relay to cause an ac. tuation of said cut-oil` relay to destroy the substation control of said line-signal and to open the circuit through the 'path in shunt4 of' said first winding of said cut-off relay.

32. VIna telephone-exchangesystem, the.

combination with a telephone-line extending IOO los

iro

by its limbs from a substation to an exchange, of switching'apparatus at the substation adapted to control the`conductive continuity of an electrical path between said 5 line-limbs7 a source -of current at the exchange for supplying talking and signalling currents to said line, said line-liinhs bein permanently connected each to an opposite terminal of said source of current, a relay having a winding permanently serially included in the first line-limb, a signal-circuit controlled by said relay, a normally closed lowresistance path in shunt of said winding of said relay'to prevent actuation thereof upon actuation of switching apparatus at the substation, a line-jack having one contact permanently directly connected to the second of said line-limbs and a second cont-act permanently connected through a second cumulative winding of said relay with the First oi: said line-limbs, cord connecting apparatus for connecting said line with another for conversation, and means whereby the insertion ot a plug of said cord connecting apparatus within said jack closes a circuit through said second jack-contact and the said second winding of said relay to cause anactuation of said relay to open the circuit through the path in shunt of said'iirst winding oi said relay whereby said relay becomes actuated to change the condition of said signal-circuit.

33. In a telephone-exchange system,'tho combination with a telephone-line extending by its limbs Jfrom a substation to an eX- change, of switching apparatus at the substation adapted to cont-rol the conductive continuity of an electrical path between said line-limbs, `a source of current at the change for supplying talking and signaling currents to said line, said line-limbs being connected each to an opposite terminal of said source of current, a relay having a wind ing serially included in the :first line-limb, a signal-circuit controlled by said. relay, a norn mally closed low-resistance path in shunt of said winding of said relay to thereby prevent actuation of said relay upon actuation of substation apparatus,a line-jack having one contact directly connected to the second of said line-limbs and a second contact connected through a second cumulative winding of said relay with the first of said line-limbs, cord connecting apparatus vfor connecting said line with another for conversation, and means whereby the insertion oi' a plug oi. said cord connecting apparatus within said jack closes a circuit through said second jack-contact and the said second winding'ot said relay to cause an actuation of said'relay to open the circuit through the path in shunt of said iirst winding said relay whereby said relaybecomes4 actuated'to change the condition of the signal-circuit, v

.34. ln' a telephone-exchange system, the

d 5 combination with a telephone-'line extending cease? by its limbs from a substation to an ex changer` of switching apparatus at the substation adapted'to control the conductive continuity of an electrical path between said line-limbs, a source oi' current at the exchange 'for supiilying talking and sigi'ialing currents to said line, said linc-lin1bs being permanently connected cach to an opposite terminal oi said source oi' current, a line-relay peinianeiuly serially included in one of said linedmbs, a line-signal controlled by said line-relay, a cut-oli relay having a winding permanei'itly serially included in the second line-limb, a nori'nally closed low-resistance path in shunt of said winding of said cut-nii relay, a line-jack having one contact permanently directly connected to one of said line-linibs and a second contact permanently connected through a second cumulative winding oi said cut-oil relay with the other of said line-limbs, cord connecting apparatus for connect ing said line with another for conversation, means whereby the insertion of a plug within said `iack closes a circuit through said second jack-contact and' the said second winding of said cut-oit relay to cause an actuation of said cut-oil relay to destroy the substation control of said linesignal and to open the circuit through the path in shunt ot said lirst win ding oi said cutofi relay, and means upon actuation ot said relay 'for closing a low-resistanco non-in ductvive electrical path between said second contact oi said jack and said second line-limb.

35. In a telephoneexcliange system, the combination with a telephone-lino extending by its limbs from a substation to an exchange, of switching apparatus at the substation adapted to control the conductive continuity of an electrical path between said line-limbs, a source oi current at the exchange for sup- )lying talking and signaling currents to said line7 said line-limbs being connected each to an opposite terminal oi said source of current, a line-relay serially included in one oi' said line-limbs, a line-signal controlled by said line-relay, a cut-ofi relay having a winding serially included in thc second line-limb, a normally closed low-resistance path in shunt of said winding of said cut-oll relay, a linejack havingl one mutant directly connected to one oi said line-limbs and a second contactv connected through a second cumulative winding oi said cut-oi? relay with thc other ot said line-limbs, cord connecting apparatus for connecting said line with another for conversation, and means whereby the insertion of a plug oi' said cord connecting apparuius within. said jack closes a circuit through said second jack-contact and the said second winding ci saidr cut-olf relay to cause au actuation of said cut-oil relay to destroy the substation control of said line-signal, to open the circuit through the path in shunt of said first winding of said cutpii' relay, and to close a low-re- IOO IXO

lses

sistance non-'inductive electrical path betweensaid second contact of said Jack and said second line-limb.,

36. In atelephone-exchange system, the

- combination with a telephone-line extending b its limbs from a substation to an exchange, o switching apparatus at the substation adapted to control the conductive continuity of an electrical path between said line-limbs,

`a source of current at the exchange for vsupi lying talking and signaling currents to said havin one contact permanently directlycon-A necte to said line-limb including said line-relay and a second contact permanently connected through a second cumulative windin of said cut-cfr` relay with the other of sai line-limbs, cord connecting apparatus for 'connecting said line with another for conversation, means whereby the insertion of a plu of said cord connecting apparatus within sai 3o jack closes a circuit through said second-j ackcontact and the saidsecond winding 0f said cut-off relay to cause an actuation of said cuto relay to destro the substation control of said line-signal an to o en the circuit through the path infshunt of said vfirst winding of said cut-off relay, and means upon actuation of said relay for closing a low-resistance non-inl ductive electrical path between said second contact of said jack and said second line-limb.

'37. In a telephone-exchange system, the

combination with a telephone-line. extending yby its limbs from a substation to an exchange, o

switching apparatus at the substation adapted to control the-conductive continuityv of an electrical path between said line-limbs,

al source of current at the lexchange for suplying talking and signaling currents tosaid ine, said linelimbs being connected each to an opposite terminal of said source of current,

' vthe insertion of a plug of said cord connect-k a line-relay serially included in one of saidline-limbs, a line-si nal controlled by said linerelay a cut-off re ay having a winding seriall included in the second line-limb, a normal y closedlow-resistance path in shunt of said winding of said cut-off relay, a line-jack having one contact directly connected. to the line-limb including said line-relay and a second contactconnected through a second cumulative Winding of said'cut-off relay with apparatus for connecting saiddine with another for conversation, and means whereby ing apparatus within said jack closes a circuit through said second jack-,contact and the said 8. DOI'- second winding of said cut-olf relay to cause van actuation of said cut-ofi relay to destroy the substation control of said line-si nal, to

open the circuit through the path in s unt of said first winding of said cut-off relay, andlto close a low-resistance non-inductive electrical path between said second contact of said j ack and said second line-limb.

'. m38. In atelephone-exchange system, the

'combination with a telephone-lineextending by its limbs from a substation to an exchange, o switching 4`apparatus at the substation adapted to control the conductivecontinuity of an electrical path between said line-limbs,

a source of current at the exchange for supplying talking and signaling currents to sai ne, said line-limbs being permanently connected eachtovan op osite terminal of i ysaid source of current, a re a having: a winding permanently serially inc uded in the first line-limb, a normall closed low-resistance path in shuntofxsai winding of said rela a line-jack having one contact permanent y directly connected to the second of said linelimbs and a second contact lpermanently connected through \a second cumulative win ing of said relay with the irst of said line-v Ilimbs, cord connecting apparatus for connecting'said line'with another for conversa-t tion, means whereby the insertion of a plug 'of said cord connecting apparatus within said jackv closes a circuit through said second ack-contact and the said second windingo said relay to cause an actuation of said re a to o pen the circuit throu h the path in s yunt of said first Winding 0I said relay, and means upon actuation of said relay adapted to close a low-resistance non-inductive electrical path between saidsecond contact of said jack and said iirst line-limb.

39. In a telephone-exchange system, the combination with a telephone-line extending b its limbs from a substation to an exchange, o? switching apparatus at the substation adapted to control the conductive 'continuityv yof an electrical path between said 'line-limbs,

a source of current at the exchange for sup- 'plyingtalking and signaling currents to said cord connecting apparatus for connecting the other of said line-limbs, cord connecting y' saidr line with another for conversationv means whereby the insertion of a plug of said cord connecting apparatus within' said jack closes a circuit through said second jack-contact and the said second Winding of said relay to cause anJ actuation of said cut-.off relay to IOO rois

Aizo

openthe circuit through the path in shunt o iirst winding of said relay, and means upon actuation of said relay adapted to close .a low-resistancenon inductive electrical path between lsaid second contact of said jack and said rst line-limb.

40.- Ina telephone-exchange system, the

I combination with a telephone-line extending g by its limbs from a substation to an exchange,

switching apparatus at the substation adapted to control the conductive continuity of an electrical path between said line-limbs,l

a source or" current at the exchange forsupv plying talking and signaling currents to said line, said line-limbs. being connected'each to a terminal of said source of current, a spring jack-contact normally connected indirectly 4With 'one line-limb, a relay having a Winding included in one line-limb, a W-resistance .pathgin shunt of said Windi of said relay,

,-cord connecting a paratus or connectin said line with anot er for conversation, an

means whereby the connection of said cord connecti apparatus with said line causes an -actuatlon' of lsaid relay to break the continuity of the low-resistance path in shunt of4 said Windir of said relay and to directly connect sai' jack-contact with the line-limb.

41. .In a tele hone-exchange system, the combination wit a telephone-line extending v bg its limbs from a substation to an exnge, of switching apparatus at` the substation adapted to control the conductive continuit `o an electrical path between said lineimbs, a source of current at the exchange'or supplying talking and signaling currents-to sai permanently connected each to an opposite terminal of said :source of current, a. lineline, said line-limbs being relay'serially included in one voi said line-` limbs, -a cut-0E relav having a windmg'in- 'eluded in the .secon closedA low-resistance Winding of said cut-o .45

line-limb a normally ath in shuntlofsaid ingy apparatus for connecting said line with another' vfor \conversation, means whereby theconnectio'n of said cord connecting'apparatus withl said line causes an actuation of said cut-off relay to ydestroy the substation control of said line-si l, and means adapted u on actuation o said cut-.on relayl to brea the continuity of. the-low-resistance path in shunt of said rst Windingof saidA cut-otrelay.

Y. 42. In a telephone-exchange system, the combination with a telephone-line extending by its limbs from a. substation t'o an. exchange, of switching rapparatus at the substation adapted to control the conductive continuity of an electrical path between said line-limbs, a source of current at the exchange for supplying talking and signaling currents to said line, said line-limbs being permanently connected each to an opposite terminal of said source of current, a line-relay relay, cord connect- Vseriall included in one of said line-limbs, a

cut-o relay having a windin included in the second line-limb, a normal y closed lowresistance ath in shunt of said winding of said cut-o `relay, cord connectin ap aratus for connecting said line With anot er or conversation,and means whereby the connection of 'said cord .connecting apparatus with said line causes an actuation of said cutoH relay to destroy the substation control of said line-signal.

43. In a telephone-exchange system, the combination with a telephone-line extending bg' its limbs from a substation to an exc. ange, ofswitching apparatus at the substation ada ted to control the conductive continuity oiJelectrical pathbetweensai d line- 'limbs, a source of current at the exchange for supplying talking and signaling currents to sai to a terminal of said source of current, a spring jack-contact normally ccnnectedindirectly with one line-limb,i a rela having a Winding included in said line-lim a low-resistance path in shunt oi said Winding, cord connectin apparatus for connecting said line with anot er for conversation, and means upon the-connection of said cord connecting a paratus with said line for causing actuation of said relay to break the continuity of the low-resistance path in shunt of said windand to directly connect said jack-contact with the line-limb.

44. In a telephone-exchange system, the combination with a telephone-line extending from a substation to an exchange, of a source' of current at the exchange for supplying talking and signaling currents to the ine, the linelimbs being connected each to aterminal of said source of current, a spring jack-contact normally connected indirectly with one linelimb, a relay having a Windin permanently included in said line-limb, a ovv-resistance path in shunt of said Winding, cord connecti -ing apparatus at the central exchange means whereby the connection of said cord connecting apparatus with said line causes -actuation of said relay to break the continuity oi the low-resistance path in shunt of said winding, and means upon actuation of said relay for causing said jack-contact to be connected directly with the line-limb.

45,. In a telephone-exchange system, the combination with a telephone-line extending from a substation to an exchan e, of a source of current at the exchange, the ine-limbs being connected each to a terminal of said source, a relay having a Winding included in one line-limb, a sprin jack-contact connected indirectly with sai line-limb through another winding of said relay, a second spring jack -contact directly connected with the other line-limb a low-resistance ath in shunt of the first relay-winding, co1 connecting apparatus at the central exchange, means line, said line-limbs being connected each IOO whereby lngs, one of said windings only the terminals of which the connection of said cord connecting apparatus with said line causes actuation of sai relay, means upon such actuatlonfor causing ythe continuity of the low-resistance ath in shunt of 'the irst winding to be roken, and additional means u on actuation of said relay for causing s'aid Rlrst spring jack-contact to be connected directly with the first line-limb.

46. In a tele hone-exchan e system the combination wit la telephoneine extending from a central exchange to a substation, of a source of current at the central exchange to the terminals of which the line-limbs are normally connected, a relay having two windp being normally included in circuit upon actuationof substation apparatus, a signal-circuit controlled by said relay, a short circuit normally about said winding to prevent actuation of said relay, cord connecting apparatus atthe centraly exchange, and means ladapted upon connection of said cord connecting a paratus with the line to cause said other Winding to be included in circuit whereby said relay is actuated and the condition of the signal-cir! cuit changed.

47. In a4 telephone-exchange system the combination with a telephone-line leading roma substation to a central exchange, of a source of current at the central exchange to the line-limbs are connected, cord connecting a paratus at .the

central exchange normal y .disconnected 3S- from the line, a relay at the central exchange aving two windings, a signal-circuit controlle ,by said relay, means adaptedupon actuation of substation apparatus for causin of said rela source of current the inclusion in circuit of only one of sai windings, means for normally maintaining a short-clrcuit path about said winding to prevent actuation of said relay, means adapted upon connection of the cord-circuit with the. line to primarily cause current to flow through the second winding whereby said relay is actuated and the condition of the signal-circuit changed, and meansadapted upon actuation for opening the short-circuit path throug the first winding.

`48. In a ltelephone-exchange system the combination with atelephone-line leading from a substation to a central exchange, of a at the central exchange to' said short-circuit pat circuit changed.

'after closing a short-circuit `second winding whereby vsaldv spring jacknected, cord connecting a central exchange normal from the line, a relay paratus at thel Y agqthe central exchange disconnected V having two windings, means ada ted'npon` actuation of substat1onapparatus `o1" causing one of said windings only to beconnected in circuit, a.signal-circuitcontrolled by said reswitching a paratus controlled/by said unchan ed, and means ada ted upon connection of t e cord-circuit witlll) the llne'i'orcausing current-flow through the second winding of the relay to cause Aactuation of the relay and of the switchin mechanism whereb Il about. the irstwvin la v 'relay and norma ly adapted to closle a short-*ij clrcuit path about said winding whereby said `relay remains inactive and the. signal-circuit ing is opened and the condition of the signal- A.

hone-exchange system, the combination wlth a telephone-line leading from a central source of current at the `central exchange, to the terminals of which the line-limbs nected, a cord-circuit at the central exchange normally disconnected from the line, a relay a't thecentral exchange havin two windings, means uponv actuation of -su station apparatus for causing the completion of a circuit through but one of said windings, means for normally closing a short-circuit path about said winding torenderthe relay inactive, a

49. In a telep 7s exchange to a substation, ofa

are conspring jack-contact normallyl indirectly connected with aline-limb through the other relay-winding, means upon connection ofthe cord-circuit with the llne for causing currentilowl through said second winding, whereby said relay becomes actuated, means upon actuation of said relay for opening the shortcircuit path about the first wlnding, andv means upon actuation of said relay for therep ontact is directly connected with the line- 1m A .l v

In witness whereof I hereunto subscribe my name this 5th day of May, A. D. 1903.

Witnesses: l

LYNN A. WILLIAMS,- HARVEY L. HANsoN.

path about the IOO HARRY G. WEBSTER 

